The present invention relates to an abnormality warning system of a high pressure pump for a direct fuel injection system in a two-cycle or four-cycle direct fuel injection engine.
As an internal combustion engine for a vehicle, a high pressure fuel injection system in which a high pressure one-fluid type injector is mounted in a combustion engine, electrically opened and closed and fuel is injected at a high pressure directly in a cylinder, has been already proposed. In this high pressure fuel injection system, fuel is discharged at a high pressure by a high pressure pump, and the fuel pressure is controlled by operating a high pressure regulator in accordance with an electric signal from a control unit. Thus, if the high pressure pump is abnormal or age-changed, the high pressure pump is controlled to be fed back so as to coincide with the fuel pressure even by largely altering the electric signal with respect to a desired fuel pressure at an initial stage. In this respect, the engine is operated without problem. However, if control of the electric signal becomes impossible so that the fuel pressure becomes insufficient and an output is actually decreased, a driver has initially felt an abnormality. If the abnormality of the high pressure pump is advanced to this state, damage of the pump is increased, the vehicle becomes impossible to travel, or damage of the engine is increased. Hence a repairing cost is remarkably increased. Consequently, it is desired to always monitor the operating state of the high pressure pump to warn at an early stage for repairing if an abnormality occurs.
Heretofore, with regard to the fore-described conventional fuel injection system, Japanese Patent Application Laid-Open 63-38639 discloses, for example, a fuel injection system where a piezoelectric actuator is driven operatively with a fuel pump at the time of starting, and a starter is driven after a fuel pressure reaches a predetermined value. Further, Japanese Patent Application Laid-Open 62-129541 discloses a fuel injection system where, if a fuel pressure is decreased to a predetermined value or less at the time of starting, an operation of a fuel injection valve is stopped.
In the former prior art, its starting characteristic is improved, and in the latter prior art, exhaust gas at the time of starting and fuel consumption are improved. However, in both the prior arts, an abnormality of the high pressure pump cannot be indicated by warning.